The invention relates to a contour standard, which can be used for calibrating a contour measuring instrument, as well as to a method for calibrating a contour measuring instrument.
The publication “Grundlagen der Rückführung von Koordinatenmessgeräten” (Foundations for Resetting Coordinate Measuring Instruments), Otto Kusko, Michal Neugebauer, PTB-Mitteilungen 117 (2007), issue 4, page 354 describes different standards and the use thereof. The standard is a test body, which serves the purpose of calibrating measuring instruments for a user and which represents a possibility, which can be used easily to pass the SI unit length to different measuring instruments in a calibrated form. Depending on the use for different measuring instruments, different test bodies can be considered thereby. The contour standard thereby refers to a method, which is described in VDI 2629 for contour measuring instruments. The desired measuring inaccuracy is thereby one micrometer for distances and approx. 0.1 degrees for angle elements. The contour standard is embodied as a plate, which encompasses a thickness of approximately 5 mm. The defined and calibrated comparison contour, which encompasses circular arcs and angles, is defined at one of the narrow sides. These contours are embodied both as depressions and also as protrusions. In response to the calibration of a contour measuring instrument, this contour is sensed and is calibrated based on the known lengths and angles of the contour of the contour measuring instrument.
In said article by PTB, a contour transfer standard is furthermore described as an alternative. It encompasses a solid ball and a prism, which are held by a support. Two precision balls made of ceramic and one Zerorud® prism, which are arranged on a support made of invar, are present in the case of the illustrated exemplary embodiment.
So-called magnification standards, for example a wave standard or a flick, are also used for restoring one-dimensional coordinate measuring instruments. These are standards having a specifically embodied form deviation. The signal transfer chain is to be examined and calibrated in the measuring instrument by means of these magnification standards. In the case of the wave standard, provision is thereby made for one or a plurality of harmonic waves on the outer side, which serve the purpose of examining and calibrating the level of the amplitudes in the signal processing of the measuring instrument. In contrast, roundness deviations are evaluated in the case of the flick. According to DE 10 2005 042 278 B4, such harmonic waves can also be provided on the jacket surface of a cylinder.